Pfizer Corporation

Paul D Weeks

Donald E Kuhla

Thomas M Brennan

Daniel P Brannegan

Robert P Allingham

John L LaMattina

Donald K Pirie

A process for the preparation of 1,1-dioxopenicillanoyloxymethyl 6-beta-aminopenicillanate which comprises reacting 1,1-dioxopenicillanoyloxymethyl 6-phenylacetamidopenicillanate or the corresponding phenoxyacetamidopenicillanate under anhydrous conditions with a halogenating agent in the presence of a reaction inert solvent to form an intermediate imino halide, addition of a primary alcohol having from one to four carbon atoms to convert the imino halide to an imino ether and subsequent hydrolysis to give the desired product.

Process and intermediates for preparation of

Processes for the preparation of the antiinflammatory agent piroxicam and intermediates leading thereto, the first of which comprises reacting N-methylsaccharin with (N-2-pyridyl)haloacetamides and alkyl haloacetates in the presence of an appropriate base to give, respectively, piroxicam and alkyl 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylate 1,1-dioxides, intermediates which can be converted into piroxicam; and the second of which comprises reacting a novel alkyl 2-(2-methyl-3-hydroxy-2,3-dihydro-1,2-benzisosulfonazol-3-yl)-2-haloacetat e with a metal hydride to give alkyl 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylate 1,1-dioxides, intermediates leading to piroxicam.

Processes for preparing piroxicam and intermediates leading thereto

A process for the debromination of 6-monobromo- and 6,6-dibromopenicillanic acid, and various derivatives thereof, by the action of a bisulfite salt. The debrominated compounds produced find various utilities, as beta-lactamase inhibitors useful in therapy in combination with known beta-lactam antibiotics, or as intermediates in the further synthesis of useful beta-lactam compounds.

Process for debromination of dibromopenicillanic acid and derivatives

A process for preparing a compound of the formula: ##STR1## wherein R is hydrogen, lower alkyl of 1 to 6 carbon atoms, lower alkenyl of 2 to 6 carbon atoms, phenyl or benzyl; and R' is lower alkyl of 1 to 6 carbon atoms which comprises contacting a compound of the formula ##STR2## wherein R and R' are defined as above at -10.degree. to 50.degree. C. with an essentially anhydrous acid selected from the group consisting of formic acid, trifluoroacetic acid, p-toluenesulfonic acid, methanesulfonic acid, citric acid, oxalic acid, chloroacetic acid, sulfuric acid, hydrochloric acid, phosphoric acid and hydrofluoric acid.

Preparation of gamma-pyrone intermediates

p-Nitrophenyl 3-bromo-2,2-diethoxypropionate, useful in the synthesis of highly functionalized small molecules and heterocycles, including pyromeconic acid and 6-methylpyromeconic acid.

p-Nitrophenyl 3-bromo-2,2-diethoxy-propionate and synthetic utility

2-Methyl-3-hydroxy-4H-pyran-4-one is prepared by contacting 1(2-furyl)-1-ethanol in aqueous solution with two equivalents of a halogen oxidant at room temperature and then heating until the hydrolysis of the formed 4-halo-dihydropyran intermediate is substantially complete. Other valuable related gamma-pyrones are prepared in analogous manner from appropriate alcohols.

Preparation of gamma-pyrones

Maltol (3-hydroxy-2-methyl-gamma-pyrone) is prepared from furfural through intermediates (a) 1-(2-furyl)-1-ethanol; (b) 2-(1-hydroxyethyl)-2,5-dialkoxy-2,5-dihydrofuran; (c) alkyl or aralkyl-2-methyl-2H-pyran-3(6H)-one; and (d) 2-alkyl or aralkyl-4-methyl-3,7-dioxabicyclo[4.1.0]heptan-5-one. Pyromeconic acid (3-hydroxy-gamma-pyrone), ethyl maltol (3-hydroxy-2-ethyl-gamma-pyrone) and other valuable 2-substituted-3-hydroxy-gamma-pyrones are prepared in an analogous manner from furfural.

2-methyl-3-hydroxy-4H-pyran-4-one is prepared by contacting 1(2-furyl)-1-ethanol in aqueous solution with two equivalents of a halogen oxidant at room temperature and then heating until the hydrolysis of the formed 4-halo-dihydropyran intermediate is substantially complete. Other valuable related gammapyrones are prepared in analogous manner from appropriate alcohols.

Intermediates for the preparation of gamma-pyrones

Processes for the preparation of the antiinflammatory agent piroxicam and intermediates leading thereto, the first of which comprises reacting N-methylsaccharin with (N-2-pyridyl)haloacetamides and alkyl haloacetates in the presence of a metal hydride to give, respectively, piroxicam and alkyl 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylate 1,1-dioxides, intermediates which can be converted into piroxicam; and the second of which comprises reacting a novel alkyl 2-(2-methyl-3-hydroxy2,3-dihydro-1,2-benzisosulfonazol-3-yl)-2-haloacetate with a metal hydride to give alkyl 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylate 1,1-dioxides, intermediates leading to piroxicam.

3-Hydroxy 2-methyl benzisothiazolines as intermediates in production of

(2-methyl-3-hydroxy-4h-pyran-4-one is prepared by contacting 1(2-furyl)-1-ethanol in aqueous solution with two equivalents of a halogen oxidant at room temperature and then heating until the hydrolysis of the formed 4-halo-dihydro-pyran intermediate is substantially complete. Other valuable related gamma-pyrones are prepared in analogous manner from appropriate alcohols.

3,4-Dihalo-tetrahydrophyran-5-one useful as intermediates for the

2-Methyl-3-hydroxy-4H-pyran-4-one is prepared by contacting 1(2-furyl)-1-ethanol in aqueous solution with two equivalents of a halogen oxidant at room temperature and then heating until the hydrolysis of the formed 4-halo-dihydropyran intermediate is substantially complete. Other valuable related gammapyrones are prepared in analogous manner from appropriate alcohols.

Gamma-pyrones are prepared by contacting a 3-halo-furfuryl alcohol or a 3-alkoxy-furfuryl alcohol with one equivalent of a halogen, peracid or peroxide oxidant and then heating until hydrolysis of the formed 4-substituted-dihydropyran intermediate is substantially complete. Maltol (2-methyl-3-hydroxy-4H-pyran-4-one) is prepared by this process from 2(1-hydroxyethyl)-3-alkoxy furans or 2(1-hydroxyethyl)-3-halo-furans. Gamma-pyrones are also prepared by contacting the corresponding 3-substituted-2,5-dialkoxy-furfuryl alcohols with acid until conversion to the gamma-pyrones is substantially complete.

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Gales Ferry, CT, United States of America

Paul D Weeks